Food allergy has reached epidemic proportions and has become a significant source of healthcare burden. Accurate in vitro methods that are efficient and easy to use to identify offending food allergens are lacking. Oral food challenge, the gold standard for food allergy assessment, is often not performed as it places the patient at risk of anaphylaxis. As such, food allergy is often identified only after an adverse reaction that could be life-threatening. We have shown that Basophil Activation Test (BAT), which measures the activation of basophils in whole blood after stimulation with specific food allergens ex vivo, is highly predictive of allergic reactions. However, current method relies on the detection of multiple markers to identify basophils and their activation status. This requires multi-color flow cytometers which are not widely accessible, and has in turn limited the broader adoption of BAT in clinical practices for food allergy assessment. There is a critical need for an alternative marker that is accurate, robust and simple, together with a rapid way to perform and analyze test results, ideally at the point of care. Our long-term goal is to develop a food allergy test that is accurate, safe, rapid, and accessible that can complement or even replace oral food challenge as the gold standard assessment of food allergy, so that: 1) food allergy can be easily identified prior to the occurrence of an adverse reaction either at the doctor's office or at home, and 2) the efficacy of immunotherapy for food allergy can be tracked more effectively. The overall objective of this pilot grant is to test the hypotheses that: 1) we can use a change in the surface charge of basophils to measure their activation status, and that the binding of avidin, a positively-charged molecule, is sufficiently accurate to replace current markers for indicating basophil activation, and 2) the test for basophil activation can be performed on a standalone biochip without compromising the accuracy of the test conventionally performed using flow cytometers. Our approach includes using whole blood samples from already clinically-proven and well-characterized peanut allergic subjects and healthy controls, and using our team's microfluidics and instrumentation capability for miniaturizing BAT onto a biochip. To test these hypotheses, we will: (Aim 1) determine whether the presence of food allergy can be determined by the avidin binding test using 100 uL of whole blood to measure basophil activation ex vivo using a conventional flow cytometer, and (Aim 2) design and validate a rapid micro-BAT (?uBAT?) on a biochip using 100 uL of whole blood to measure basophil activation in the presence of food allergen ex vivo.